void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
const ObjCAtTryStmt &S,
llvm::Constant *beginCatchFn,
llvm::Constant *endCatchFn,
llvm::Constant *exceptionRethrowFn) {
// Jump destination for falling out of catch bodies.
CodeGenFunction::JumpDest Cont;
if (S.getNumCatchStmts())
Cont = CGF.getJumpDestInCurrentScope("eh.cont");
CodeGenFunction::FinallyInfo FinallyInfo;
if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
FinallyInfo.enter(CGF, Finally->getFinallyBody(),
beginCatchFn, endCatchFn, exceptionRethrowFn);
SmallVector<CatchHandler, 8> Handlers;
// Enter the catch, if there is one.
if (S.getNumCatchStmts()) {
for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
Handlers.push_back(CatchHandler());
CatchHandler &Handler = Handlers.back();
Handler.Variable = CatchDecl;
Handler.Body = CatchStmt->getCatchBody();
Handler.Block = CGF.createBasicBlock("catch");
// @catch(...) always matches.
if (!CatchDecl) {
Handler.TypeInfo = 0; // catch-all
// Don't consider any other catches.
break;
}
Handler.TypeInfo = GetEHType(CatchDecl->getType());
}
EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
}
// Emit the try body.
CGF.EmitStmt(S.getTryBody());
// Leave the try.
if (S.getNumCatchStmts())
CGF.popCatchScope();
// Remember where we were.
CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
// Emit the handlers.
for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
CatchHandler &Handler = Handlers[I];
CGF.EmitBlock(Handler.Block);
llvm::Value *RawExn = CGF.getExceptionFromSlot();
// Enter the catch.
llvm::Value *Exn = RawExn;
if (beginCatchFn) {
Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
cast<llvm::CallInst>(Exn)->setDoesNotThrow();
}
CodeGenFunction::RunCleanupsScope cleanups(CGF);
if (endCatchFn) {
// Add a cleanup to leave the catch.
bool EndCatchMightThrow = (Handler.Variable == 0);
CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
EndCatchMightThrow,
endCatchFn);
}
// Bind the catch parameter if it exists.
if (const VarDecl *CatchParam = Handler.Variable) {
llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
CGF.EmitAutoVarDecl(*CatchParam);
CGF.Builder.CreateStore(CastExn, CGF.GetAddrOfLocalVar(CatchParam));
}
CGF.ObjCEHValueStack.push_back(Exn);
CGF.EmitStmt(Handler.Body);
CGF.ObjCEHValueStack.pop_back();
// Leave any cleanups associated with the catch.
cleanups.ForceCleanup();
CGF.EmitBranchThroughCleanup(Cont);
}
// Go back to the try-statement fallthrough.
CGF.Builder.restoreIP(SavedIP);
// Pop out of the finally.
if (S.getFinallyStmt())
FinallyInfo.exit(CGF);
if (Cont.isValid())
CGF.EmitBlock(Cont.getBlock());
}
/// BuildScopeInformation - The statements from CI to CE are known to form a
/// coherent VLA scope with a specified parent node. Walk through the
/// statements, adding any labels or gotos to LabelAndGotoScopes and recursively
/// walking the AST as needed.
void JumpScopeChecker::BuildScopeInformation(Stmt *S,
unsigned &origParentScope) {
// If this is a statement, rather than an expression, scopes within it don't
// propagate out into the enclosing scope. Otherwise we have to worry
// about block literals, which have the lifetime of their enclosing statement.
unsigned independentParentScope = origParentScope;
unsigned &ParentScope = ((isa<Expr>(S) && !isa<StmtExpr>(S))
? origParentScope : independentParentScope);
unsigned StmtsToSkip = 0u;
// If we found a label, remember that it is in ParentScope scope.
switch (S->getStmtClass()) {
case Stmt::AddrLabelExprClass:
IndirectJumpTargets.push_back(cast<AddrLabelExpr>(S)->getLabel());
break;
case Stmt::ObjCForCollectionStmtClass: {
auto *CS = cast<ObjCForCollectionStmt>(S);
unsigned Diag = diag::note_protected_by_objc_fast_enumeration;
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope, Diag, 0, S->getLocStart()));
BuildScopeInformation(CS->getBody(), NewParentScope);
return;
}
case Stmt::IndirectGotoStmtClass:
// "goto *&&lbl;" is a special case which we treat as equivalent
// to a normal goto. In addition, we don't calculate scope in the
// operand (to avoid recording the address-of-label use), which
// works only because of the restricted set of expressions which
// we detect as constant targets.
if (cast<IndirectGotoStmt>(S)->getConstantTarget()) {
LabelAndGotoScopes[S] = ParentScope;
Jumps.push_back(S);
return;
}
LabelAndGotoScopes[S] = ParentScope;
IndirectJumps.push_back(cast<IndirectGotoStmt>(S));
break;
case Stmt::SwitchStmtClass:
// Evaluate the C++17 init stmt and condition variable
// before entering the scope of the switch statement.
if (Stmt *Init = cast<SwitchStmt>(S)->getInit()) {
BuildScopeInformation(Init, ParentScope);
++StmtsToSkip;
}
if (VarDecl *Var = cast<SwitchStmt>(S)->getConditionVariable()) {
BuildScopeInformation(Var, ParentScope);
++StmtsToSkip;
}
LLVM_FALLTHROUGH;
case Stmt::GotoStmtClass:
// Remember both what scope a goto is in as well as the fact that we have
// it. This makes the second scan not have to walk the AST again.
LabelAndGotoScopes[S] = ParentScope;
Jumps.push_back(S);
break;
case Stmt::IfStmtClass: {
IfStmt *IS = cast<IfStmt>(S);
if (!(IS->isConstexpr() || IS->isObjCAvailabilityCheck()))
break;
unsigned Diag = IS->isConstexpr() ? diag::note_protected_by_constexpr_if
: diag::note_protected_by_if_available;
if (VarDecl *Var = IS->getConditionVariable())
BuildScopeInformation(Var, ParentScope);
// Cannot jump into the middle of the condition.
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope, Diag, 0, IS->getLocStart()));
BuildScopeInformation(IS->getCond(), NewParentScope);
// Jumps into either arm of an 'if constexpr' are not allowed.
NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope, Diag, 0, IS->getLocStart()));
BuildScopeInformation(IS->getThen(), NewParentScope);
if (Stmt *Else = IS->getElse()) {
NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope, Diag, 0, IS->getLocStart()));
BuildScopeInformation(Else, NewParentScope);
}
return;
}
case Stmt::CXXTryStmtClass: {
CXXTryStmt *TS = cast<CXXTryStmt>(S);
{
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_cxx_try,
diag::note_exits_cxx_try,
TS->getSourceRange().getBegin()));
if (Stmt *TryBlock = TS->getTryBlock())
BuildScopeInformation(TryBlock, NewParentScope);
}
// Jump from the catch into the try is not allowed either.
for (unsigned I = 0, E = TS->getNumHandlers(); I != E; ++I) {
CXXCatchStmt *CS = TS->getHandler(I);
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_cxx_catch,
diag::note_exits_cxx_catch,
CS->getSourceRange().getBegin()));
BuildScopeInformation(CS->getHandlerBlock(), NewParentScope);
}
return;
}
case Stmt::SEHTryStmtClass: {
SEHTryStmt *TS = cast<SEHTryStmt>(S);
{
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_seh_try,
diag::note_exits_seh_try,
TS->getSourceRange().getBegin()));
if (Stmt *TryBlock = TS->getTryBlock())
BuildScopeInformation(TryBlock, NewParentScope);
}
// Jump from __except or __finally into the __try are not allowed either.
if (SEHExceptStmt *Except = TS->getExceptHandler()) {
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_seh_except,
diag::note_exits_seh_except,
Except->getSourceRange().getBegin()));
BuildScopeInformation(Except->getBlock(), NewParentScope);
} else if (SEHFinallyStmt *Finally = TS->getFinallyHandler()) {
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_seh_finally,
diag::note_exits_seh_finally,
Finally->getSourceRange().getBegin()));
BuildScopeInformation(Finally->getBlock(), NewParentScope);
}
return;
}
case Stmt::DeclStmtClass: {
// If this is a declstmt with a VLA definition, it defines a scope from here
// to the end of the containing context.
DeclStmt *DS = cast<DeclStmt>(S);
// The decl statement creates a scope if any of the decls in it are VLAs
// or have the cleanup attribute.
for (auto *I : DS->decls())
BuildScopeInformation(I, origParentScope);
return;
}
case Stmt::ObjCAtTryStmtClass: {
// Disallow jumps into any part of an @try statement by pushing a scope and
// walking all sub-stmts in that scope.
ObjCAtTryStmt *AT = cast<ObjCAtTryStmt>(S);
// Recursively walk the AST for the @try part.
{
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_objc_try,
diag::note_exits_objc_try,
AT->getAtTryLoc()));
if (Stmt *TryPart = AT->getTryBody())
BuildScopeInformation(TryPart, NewParentScope);
}
// Jump from the catch to the finally or try is not valid.
for (unsigned I = 0, N = AT->getNumCatchStmts(); I != N; ++I) {
ObjCAtCatchStmt *AC = AT->getCatchStmt(I);
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_objc_catch,
diag::note_exits_objc_catch,
AC->getAtCatchLoc()));
// @catches are nested and it isn't
BuildScopeInformation(AC->getCatchBody(), NewParentScope);
}
// Jump from the finally to the try or catch is not valid.
if (ObjCAtFinallyStmt *AF = AT->getFinallyStmt()) {
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_objc_finally,
diag::note_exits_objc_finally,
AF->getAtFinallyLoc()));
BuildScopeInformation(AF, NewParentScope);
}
return;
}
case Stmt::ObjCAtSynchronizedStmtClass: {
// Disallow jumps into the protected statement of an @synchronized, but
// allow jumps into the object expression it protects.
ObjCAtSynchronizedStmt *AS = cast<ObjCAtSynchronizedStmt>(S);
// Recursively walk the AST for the @synchronized object expr, it is
// evaluated in the normal scope.
BuildScopeInformation(AS->getSynchExpr(), ParentScope);
// Recursively walk the AST for the @synchronized part, protected by a new
// scope.
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_objc_synchronized,
diag::note_exits_objc_synchronized,
AS->getAtSynchronizedLoc()));
BuildScopeInformation(AS->getSynchBody(), NewParentScope);
return;
}
case Stmt::ObjCAutoreleasePoolStmtClass: {
// Disallow jumps into the protected statement of an @autoreleasepool.
ObjCAutoreleasePoolStmt *AS = cast<ObjCAutoreleasePoolStmt>(S);
// Recursively walk the AST for the @autoreleasepool part, protected by a
// new scope.
unsigned NewParentScope = Scopes.size();
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_objc_autoreleasepool,
diag::note_exits_objc_autoreleasepool,
AS->getAtLoc()));
BuildScopeInformation(AS->getSubStmt(), NewParentScope);
return;
}
case Stmt::ExprWithCleanupsClass: {
// Disallow jumps past full-expressions that use blocks with
// non-trivial cleanups of their captures. This is theoretically
// implementable but a lot of work which we haven't felt up to doing.
ExprWithCleanups *EWC = cast<ExprWithCleanups>(S);
for (unsigned i = 0, e = EWC->getNumObjects(); i != e; ++i) {
const BlockDecl *BDecl = EWC->getObject(i);
for (const auto &CI : BDecl->captures()) {
VarDecl *variable = CI.getVariable();
BuildScopeInformation(variable, BDecl, origParentScope);
}
}
break;
}
case Stmt::MaterializeTemporaryExprClass: {
// Disallow jumps out of scopes containing temporaries lifetime-extended to
// automatic storage duration.
MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(S);
if (MTE->getStorageDuration() == SD_Automatic) {
SmallVector<const Expr *, 4> CommaLHS;
SmallVector<SubobjectAdjustment, 4> Adjustments;
const Expr *ExtendedObject =
MTE->GetTemporaryExpr()->skipRValueSubobjectAdjustments(
CommaLHS, Adjustments);
if (ExtendedObject->getType().isDestructedType()) {
Scopes.push_back(GotoScope(ParentScope, 0,
diag::note_exits_temporary_dtor,
ExtendedObject->getExprLoc()));
origParentScope = Scopes.size()-1;
}
}
break;
}
case Stmt::CaseStmtClass:
case Stmt::DefaultStmtClass:
case Stmt::LabelStmtClass:
LabelAndGotoScopes[S] = ParentScope;
break;
default:
break;
}
for (Stmt *SubStmt : S->children()) {
if (!SubStmt)
continue;
if (StmtsToSkip) {
--StmtsToSkip;
continue;
}
// Cases, labels, and defaults aren't "scope parents". It's also
// important to handle these iteratively instead of recursively in
// order to avoid blowing out the stack.
while (true) {
Stmt *Next;
if (SwitchCase *SC = dyn_cast<SwitchCase>(SubStmt))
Next = SC->getSubStmt();
else if (LabelStmt *LS = dyn_cast<LabelStmt>(SubStmt))
Next = LS->getSubStmt();
else
break;
LabelAndGotoScopes[SubStmt] = ParentScope;
SubStmt = Next;
}
// Recursively walk the AST.
BuildScopeInformation(SubStmt, ParentScope);
}
}